Dynamic evaluation of prolactin secretion in essential hypertension: evidence against hypothalamic-pituitary...

Hyperprolactinemia has previously been noted in patients with essential hypertension and it has been suggested that the increased PRL levels in this condition may reflect reduced central dopaminergic activity. In the present study, PRL secretion was evaluated in 17 patients with essential hypertension and in 9 normal controls as an indirect index of hypothalamic-pituitary dopaminergic activity. PRL levels were measured basally, at night, and after TRH (200 micrograms, iv), metoclopramide (10 mg, orally), and L-dopa (500 mg, orally). Basal PRL levels were similar in both groups [essential hypertension, 301.2 +/- 176.2 microunits/ml; controls, 334.2 +/- 98.8 microunits/ml (mean +/- SD)]. No differences in PRL levels were found after TRH, L-dopa, and metoclopramide or during sleep between the 2 groups. When the patients were classified according to their PRA, no differences were noticed in either basal levels or the patterns of PRL response. It is concluded that PRL secretion is normal in patients with essential hypertension, which could be indirect evidence against reduced hypothalamic-pituitary dopaminergic activity in this disease. However, minor abnormalities not detected by PRL measurements could be involved in the pathogenesis of essential hypertension.